Wireless telegraphy.



Patented Nov. 26, 1912.

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REGINALD A. FESSENDEN, 0F BRANT ROCK, MASSACHUSETTS, ASSIGNOR TONATIONAL ELECTRIC SIGNALING .COMPANY, OF PITTSBURGH, PENNSYLVANIA, ACORPORA- TION OF NEW JERSEY.

WIRELESS TELEGRAPHY.

I,4t5,782. Original application filed June 16,

Specification of Letters Patent.

Patented Nov. as, role.

1910. Serial No. 540,735.

To all whom it may concern:

Be it known that I, REGINALD A. FnssEN- DEN, a citizen of the UnitedStates, residing at Brant Rock, in the State of Massachusetts, haveinvented certain new and useful Improvements in Wireless Telegraphy, ofwhich the following is a specification.

My invention relates to the art of signaling by electromagnetic waves,and its primary objects are to increase the sensitiveness and efliciencyof receiving devices for signaling thereby.

More especially it is designed to make use of electrostatic efi'ects inthe construction of receivers.

I In the accompanying drawing Figure 1 is a diagram of a receiveroperating by an electrostatically charged wire, and Fig. 2 is a diagramshowing a receiver with means for recording a message.

A form of static telephone receiver described by Dolbear in his UnitedStates Patent No. 350299, of 1882, has been used in experimenting in.receiving wireless signals in various forms in which the diaphragms weremade of sheet metal either plain or covered with an electrifieddielectric, and also with a dielectric having a metallic coating on theside next to the fixed plate, these receivers, however, have beeninsensitive and have not come into practical use. I have discovered thatstatic receivers can be made extremely sensitive by use of certainconstructions and methods of operation, some of which are disclosed inmy co-pending application No. 438725 of June 16th, 1908, of which thisapplication is a division. I herein show a form in which I useelectrostatically charged wires or filaments, which by change ofposition due to change of the charge, produce a signal, which may berecorded.

In Fig. 1, I show an antenna 105 grounded at 115 and having in circuitthe primary 106 of a transformer whose secondary is 107. In circuit withthe secondary is an adjustable inductance 118, and an adjustablecondenser 119. The leads 128 and 127 are connected to two extremely finewires of filaments 121, 122, which are mounted in a glass vessel 120 inany convenient way. They are preferably made of aluminum or else ofquartz with a'silver coating. Their tension may be adjusted by means ofan armature 123which is pulled down by the efi'ect of the electromagnet1% excited by battery 125, whose current may be adjusted by theresistance 126. In proximity to the wires 121, 122, I place parallellarger conductors 129 and 130, ad usting their distances from the wiresvery carefully, since I have found that there is a certain criticaldistance at which the apparatus is very sensitive, while thesensitiveness falls ofi if these larger conductors are either closer orfarther away than the critical distance. These conductors 129, 130, maybe connected to a local exciting circuit containing a high frequencydynamo 131. Resistances 132, 133,

form an adjustable potentiometer for regu;

lating the voltage to which conductors 129, 130, are raised, while avariable condenser 134 is used to also modify the intensity and at thesame time alter the phase. I provide switches 138, 139, to operate thedevice and it will be understood that when electromagnetic waves passthrough the primary 106 they will generate oscillations in the secondarycircuit 107, 118, 119, and the wires 121, 122, will by the electrostaticeffects be caused to change their relative position. Such change ofposition may be either observed or recorded in any convenient or obviousway. It will also be noted that if the wires 121, 122 are continuouslygiven a certain rate of electrostatic charge in the neighborhood of theperiodicity of excitation of the wires 129 and 130, beats will beproduced of audible or otherwise recordable frequency, according to mywell known heterodyne method. This static charging with neighboringfrequency to produce beats, may be called heterostatic charging. By useof the switches 135, 136, and 137, the circuits may be grounded asindicated, while by switches 138 and 139 one or more of the sides of thecircuits may be opened. I have found that by suitable use of theseswitches the efiect of atmospheric electricity may be cut out.

In Fig. 2, I show a convenient form of recording apparatus for makin apermanent record of the signals receive as above described. The diagramrepresents a Nernst glower at 140 excited by a source 141 and by meansof lenses 142 and 143 projecting a ray of light on a moving strip ofphotographic film 145, this ray of light passes through a perforateddiaphragm 144 and casts an image of the wires 120 and 121 of Fig. 1, sothat the signal is recorded by relative change of position of thesewires as above described. For example, if the received oscillationsformed beats with the oscillations locally produced by the heterodynecircuit of Fig. 1, such beats will be of low enough periodicity toeasily record on the photographic film.

Having thus described my invention and illustrated its use, I claim thefollowing:

1. An electrical indicator comprising a fixed conducting surface and aflexible conducting wire mounted in proximity thereto and means tocharge the said surface and wire heterostatically to produce a varyingfield of force and cause the Wire to move.

2. In wireless telegraphy apparatus, the combination with a fixedconducting sur'- face and means at the receivin station to produce acontinuous train 0 high frequency oscillations thereon, a movablymounted fine wire supported in proximity to the said surface and meansto continuously excite it by high frequency oscillations,

whereby the wire and surface are electrostatically attracted, and meansto produce an indication by the influence of the combined excitations ofsaid surface and said wire.

3. A receiver for Wireless telegraphy comprising a fixed conductingsurface and means to excite it with locally produced high frequencyoscillations, a fine wire supported in proximity to said surface andmeans to charge it by received oscillations periodically at oscillationfrequencies neighboring the frequency of locally produced oscillations,whereby to vary the electrostatic-attraction between the surface and thewire, and means to photograph the resulting movements of the wire,substantially as described.

- In testimony whereof I have hereunto signed my name in the presence ofthe two subscribed witnesses.

REGINALD A. FESSENDEN.

Witnesses:

JESSIE ETTA BENT, FLORENCE MAY LYON.

